Automobile speed-controlling mechanism



United States Patent a corporation of Delaware [54] AUTOMOBILESPEED-CONTROLLING MECHANISM 6 Claims, 6 Drawing Figs.

[52] U.S. Cl 180/98, 3 18/8, 180/105 [51] Int. Cl 860k 31/00 [50] Fieldof Search l80/98,

[56] References Cited UNITED STATES PATENTS 2,594,739 4/l 952 DavisPrimary Examiner-Kenneth H. Betts Attorney-Kinney, Alexander, Sell,Steldt & Delahunt ABSTRACT: A frequency differential-accumulator for usein controlling the speed of an automobile by comparing, as to frequency,a standard signal and a signal that is derived in magnetic-flux-sensorson the automobile by passage of the sensors through a sequence ofmagnetic fields located along a highway according to a predeterminedfrequency. The frequency differential-accumulator includes twosynchronous electric motors, one supplied the standard signal and theother supplied the flux-sensor-derived signal, and the motors arephysically connected so that part of the motor supplied theflux-sensor-derived signal moves in proportion to any lack ofcorrespondence between the frequency of the standard and derivedsignals. This movement is used to control the carburetor throttle valveof the automobile.

AUTOMOBILE SPEED-CONTROLLING MECHANISM BACKGROUND OF THE INVENTION Thedesire to make automobile driving on highways more safe and easy has ledto various suggestions for automatically guiding automobiles. Several ofthese suggestions have inin the sensors that is dependent as tofrequency on the spacing of the fields and the rate of travel of theauto. This generated signal is then compared as to frequency with astandard frequency and any difference is used to control the speed ofthe auto.

The devices proposed for controlling the speed of the automobile withthe signal derived in the flux-sensors have not been wholly satisfactoryfor their job. One type of previously, suggested speed-controllingdevice incorporates a frequency discriminator. The discriminator istuned to a standard frequency, and whenever the frequency of the-derivedsignal fed to the discriminator is either greater or lower than thestandard frequency, a direct current is developed in the discriminator.This direct current signal is fed to a 'servomechanism that operates thecar's throttle, slowing the car when the frequency of the derived signalis higher than the standard frequency and accelerating the car when thefrequency of the derived signal is lower than the standard frequency.

A major disadvantage of use of a frequency discriminator in anautomobile speed-controlling device is that the discriminator has nomemory" for the error that may have developed between the location a carshould have at any time and the position it actually has. Thus, when acar is lagging behind the speed that it should have-because it istraveling uphill, for example-the discriminator will develop a signalthat will cause the automobile to increase its speed to the speed itshould be traveling. But the carwill not necessarily make up the groundit lost while traveling atthe slow speed. Thus, if adjacent cars travelfor many miles under the control of speed-controlling devices based on afrequency discriminator, the distance between the carswill not beprecisely controlled. An even flow of traffic will not be obtained, andinstead of the traffic being guided wholly automatically, some operationmay be required by the drivers.

SUMMARY OF THE INVENTION The present invention provides aspeed-controlling device that accurately and simply controls the speedof an automobile with a signal derived in flux-sensors as describedabove, and that also has a memory for any difference between the actualand correct positions of the controlled automobile; as a result of this"memory," a speed-controlling device of this invention returns thecontrolled auto to its correct position. This speed-controlling deviceincorporates a frequency differential-accumulator, which is a devicethat includes two synchronous electric motors, with the windings of oneof the motors, called the reference" motor, being supplied with areference signal having a standard frequency and the windings of theother, actuating," motor being supplied by the fluxsensor-derivedsignal. It will be seen that the rates at which the rotating parts ofthe motors are driven by the motors correspond and lack correspondencewhen the frequency of the derived and standard signals correspond andlack correspondence, respectively. Connection means physically connectthe reference and actuating motors so that one of the stator andarmature of the actuating motor is fixed with respect to one of thestator and armature of the reference motor, and so that the rotation ofthe other of the stator and armature of the actuating motor differs fromthe rotation of the other of the stator and armature of the referencemotor (which may be no rotation) in proportion to any lackiofcorrespondence between the driving rates of the actuating and referencemotors. An output member is drivingly connected to the other of thestator and armature of the actuating motor so that the output member ismoved in proportion to any lack of correspondence between the drivingrates of the actuating and reference motors. Linkage means link theoutput member to the carburetor throttle valve of the automobile so thatmovement of the output member opens or closes the throttle valve whenthe frequency of the flux-sensor-derived signal is lower or higher,respectively, than the frequency that corresponds with the frequency ofthe standard signal.

In a specific, exemplary embodiment of the invention, the stator of thereference motor is fixed'with respect to the automobile body byfastening the external housing of the motor to the automobile body. Arigid couple connects the armature of the reference motor to thearmature of the actuating motor;

the stator of the actuating motor is supported by the armature of theactuating motor and is otherwise unfixed. Whenever the frequency of theflux-sensonderived signal deviates from the frequency of the standardsignal supplied to the windings of the reference motor, the frequency ofthe electromotive force developed in the actuating motor-that is, thedriving rate of that motordoes not correspond with the rate at which thearmature of that motor is actually being turned through its connectionto the armature of the reference motor. The result is that the stator ofthe actuating motor rotates slightly to maintain the relationship to thearmature of that motor that is consistent with the frequency'of theelectromotive force, or the driving rate, developed within the actuatingmotor. As will be seen, the rotation of the stator of the actuatingmotor is proportional to any lack of correspondence between the drivingrates of the actuating and reference motors.

The output member is connected to the stator of the actuating motor, andis also linked to the carburetor throttle valve; thereby the turning ofthe stator of the actuating motor controls the speed of the auto. Aswill subsequently be explained in more detail, the angle, if any,through which the output member has turned at any instant in time is ameasure of the extent to which the auto is displaced from the positionit actually should have at that instant. Whenever the speed of the autohas been corrected sufficiently that the output member has returned toits original position, the auto then also will have returned to theposition it should have at that instant in time. Since the stator of theactuating motor, and the output member connected to it, always tend toreturn to their original position, the auto always tends to return toits correct" position.

DRAWINGS FIG. 1 is a top view of one-half of a limited-access, six-lane,divided highway on which travel of an automobile equipped with aspeed-controlling device of this invention may be controlled;

FIG. 2 is a schematic elevation of a portion of an auto automaticallyguided according to this invention;

FIG. 3 is a view of the auto of FIG. 2 taken along the line 3-3 in FIG.2;

FIG. 4 is a schematic perspective view of a frequencydifferential-accumulator of this invention;

FIG. 5 is a schematic elevation view of a different frequencydifierential-accumulator of the invention; and

FIG. 6 is a schematicwiring diagram of electric circuitry useful tooperate a frequency differential-accumulator of this invention.

DETAILED DESCRIPTION FIG. 1 shows a top view of the right-hand half 10of a limited-access, six-lane, divided highway of this invention. Of thethree lanes 10a, 10b, and that form the right-hand half of the highway,two, 1011 and 10b, are not controlled and cars may travel along them atany desired speed within the range established by statuto'ry speedlimits, and cars may pass one another. Theinside lane, that is, the lane100 which is next to the center divider of the highway, is controlled.

The lane We of the illustrated controlled highway, has a continuousstripe ll of magnetizable material down the center, magnetized with asequence of magnetic poles that are generally spaced from one anotherbetween 3 and 16 inches. Preferably the stripe 11 is formed from amagnetizable paint that comprises magnetizable particles such asferromagnetic dxi'des or iron filings dispersed in a vehicle thatincludes an organic polymeric film-forming binder material dissolved ina volatile solvent. The magnetizable stripe 11 can also comprise a metalfoil or a performed organic polymeric sheet in which magnetizableparticles are embedded or on which they are coated. On other controlledhighways the sequence of magnetic fields may be formed by conductorsburied in the highway or other means.

An automobile or other vehicle adapted to be controlled according tothis invention, such as the vehicle 25 shown in FIGS. 2 and 3, includesat least one magnetic-field or fluxsensor, generally located near thesurface of the highway (preferably within 8 inches) so as to minimizethe strength of field that must be established by the stripe 11 andminimize the amplification required for the signal developed by thefluxsensor. The vehicle 25 shown in FIGS. 2 and 3 has two fluxsensors 26and 27, laterally spaced as shown in FIG. 3. The flux-sensors may takevarious forms, but those illustrated each include two large vanes 28 and29 of ferromagnetic material formed from the same plate or a sandwich ofplates. The vanes, which gather and concentrate the magnetic fieldthrough which they pass, are connected by a narrow intermediate portion30 of the plate or sandwich of plates, and a conductive coil 31 iswrapped around this connecting intermediate portion of the plates.

The signals developed in the two flux-sensors 26 and 27 by passagethrough the magnetic fields above a magnetized stripe l1 areamplifiedand combined and then fed to a frequency differential-accumulator ofthis invention. One frequency differential-accumulator of thisinvention, 33, is illustrated in FIG. 4 and includes reference andactuating synchronous electric motors 34 and 35, respectively, whosearmatures are fixed with respect to one another by connecting theirshafts, 36 and 37, respectively, with a rigid coupling 38. The externalhousing 40 of the reference synchronous motor 34 of this illustrativefrequency differential-accumulator is mounted on and fixed with respectto the body 41 of the automobile 25, and the windings of the stator ofthe reference motor are supplied through conductors 39 from a source ofalternating current having a standard reference frequency (such as areference oscillator that incorporates a precision tuning fork). Theactuating synchronous motor 35 is supported only by the connection ofits shaft 37 with the shaft 36 of the reference motor, and the windingsof the stator of the actuating motor are supplied through conductors 32by the signal developed in the flux-sensors 26 and 27. The shaft of thereference motor 34 is driven at a constant rate determined by thereference frequency of the signal supplied the first motor. Aspreviously explained, if the frequency of the flux-sensor-derived signalis different from the frequency of the standard signal, the frequency ofthe electromotive force developed in the stator of the actuating motor35 does not correspond to the rate at which the actuating motor shaft isactually being driven by the reference motor. The result is that thehousing or body 42 of the actuating motor 35 rotates to maintain itsproper relationship to its shaft 37.

A lever 44 serving as an output member is fixed to the body 42 of theactuating synchronous motor 35 and turns as the body of the motor turns.A linkage 45, including an electromagnetic coupling 65 (not shown inFIG. 4) that may be deenergized when the auto is not being controlled bythe automatic guidance mechanism, extends from the lever 44 to thethrottle valve 46 of the automobiles carburetor so that rotation of thebody42 of the actuating motor 35 causes an opening or closing of thecarburetor throttle valve. If the vehicle 25 is traveling at a speedbelow'the standard one for the highway being traveled, the frequency ofthe signal generated in the flux sensors 26 and 27 will be less than thestandard frequency and the body of the actuating motor will rotatecounterclockwise in FIG. 4 to open the throttle valve. The speed of Ithe vehicle 25 will then increase, until the frequency of the derivedsignal is slightly more than the frequency of the stan-" dard signalwhereupon the body of the actuating synchronous motor will rotateclockwise in FIGf4toclose the throttle valve somewhat. After a shorttime, the body of the actuating motor I will find its proper location tomaintair i th'eispeed of the automobile at the standard speed, afterwhich he lever and carburetor throttle valve will tend to remain afasteady position so long as the standard speed for the highway remainsconstant.

35 and the attached lever 44 must rotate freely for satisfactoryoperation of the frequency differentialaccumulator 33. Stops 47 arefixed on both sides of the lever 44in the path that the lever travels todefine the extent of pivoting of the lever. In the have at any instantin time. ln the embodiment of the invention shown in FIG. 4, thismemory'manifests itself as the angle which the lever 44 assumes at anyparticular instant. As an example, assume that the actuating andreference synchronous motors 34 and 35 each have 72 poles. For eachpolarity reversal of the electric signals supplying the motors, therotating parts of the motors will rotate 5 degrees. Suppose that themagnetic poles along the highway are spaced at 9 inch intervals. If forsome reason such as travel uphill, the vehicle loses speed so that itlags 27 inches (3 reversals) in comparison to the location it shouldhave at that instant,.the armature of the actuating motor 35 wouldordinarily have rotated 15 degrees less than the armature of thereference motor 34. But, since the armature of the actuating motor 35 isrigidly coupled to the armature of the reference motor, the armature ofthe actuating motor rotates through the same angle as the armature ofthe reference motor. To maintain the proper relationship between thestator and armature of the actuating motor, the stator or body of themotor must therefore turn 15 degrees from its original position, therebyadvancing the throttle valve to increase the speed of the auto. Thespeed of the auto remains higher than its original speed until thestator or body of the actuating motor 35 returns to its originalposition. At that point, the actuating motor has experienced the samenumber of polarity reversals as the reference motor; that is, the threelagging pole intervals have been recovered, and the automobile is in theexact position that it should be in. The

synchronous motors will be directly proportional to the.

number of changes in polarity traversed by the automobile, and thatnumber will be directly proportional to the distance traveled by the carif the standard speed does not vary over the- 1 course. Accordingly,odometers thatwill measure distance traveled independently of tireinflation or wheel slip may be driven by the frequencydifferential-accumulator of this invention. Whether or not the speed ofthe auto varies over .the

route, a totalizing counter may be used to accurately inform-- thedriver of his arrival at various exits, for which he has learned thenumber that should appear on the counter from a map, signs, or brochuresreceived at a tollway entrance.

As will be understood, the body 42 of the actuating motorautomaticguidance If the frequency of the standard current is derived from anelectrically driven tuning fork having an accuracy of 0.001 percent,which is readily obtainable, two adjacent cars traveling under thecontrol of speed controlling devices of this invention over a coursehaving poles at approximately 9-inch intervals should not changedistance by more than I 1 feet in 100 miles. Instead of a source ofstandard frequency in an automobile, the standard frequency could bebroadcast by radio and received by a radio receiver in the auto, therebyeliminating even this small error.

Frequency differential-accumulators of the invention can take severalforms other than the one illustrated in FIG. 4. lnstead of beingdirectly connected to the body 42 of the synchronous motor, the lever 44maybe connected to the body 42 by a gear train that reduces the angulartravel of the lever 44 for a given angle of rotation of the body 42.Such a reduction in the travel of the lever 44 is especially desirablewhere synchronous motors having a small number of poles are used, inwhich case the lagging or advancing of the car by several intervalsbetween the poles along the magnetizable stripe means a large angularrotation of the body 42. Further,

if the shaft, rather than the body, of the reference synchronous motoris fixed with respect to the automobile, and the bodies of the twomotors coupled to one another, then the shaft of the second synchronousmotor carries the lever that controls the carburetor throttle valve. Or,if the body of the first motor is fixed to the automobile body; but theshaft of the first motor is coupled to the body of the'second motor,then the lever 44 will be carried on the shaft of the second motor.

Also, the reference and actuating motors need not have the same numberof poles; if, for example, the actuating motor has twice the number ofpoles that the reference motor has, the frequency of theflux-sensor-derived signal that corresponds to the frequency of thestandard signal when the automobile is traveling at the control speedwill be twice the standard frequency. Further, instead of using arigidcouplingto connect the parts of the reference and actuating motors, agear train may fix the two parts with respect to one another, in whichcase the frequency of the flux-sensor-derived signal that corresponds tothe standard frequency may not be equal to the standard frequency.

In another frequency differential-accumulator of the invention, 100,illustrated in FIG. 5, the bodies 101 and 102 of reference and actuatingsynchronous motors, 103 and 104, respectively, are fixed with respect toone another by fixing them both to the automobile body 105. The shafts106 and 107 of the motors 103 and 104 are connected by a differentialgeartrain that includes bevel gears 108 and 109 carried on the shafts106 and 107, respectively, which both mesh with a third bevel gear 110.The gear 110 is rotatably supported on a lever 111 that is pivotablyattached to a yoke 112 by a pin 113. A link 114 connects the free end ofthe lever 111 to the carburetor throttle valve. When a difference in therate of rotation of the shafts 106 and 107 occurs as a result of adifierence between the frequencies of the flux-sensor-derived signal andthe standard signal, the gear 110 is caused to advance in an are aboutthe pin 113. The resulting movement of the lever or output member 111,through the link 114, opens or closes the carburetor throttle valve.

Arrangements other than a physical connection are contemplated forcoupling the frequency differential-accumulator to the carburetorthrottle and valve. For example, the lever 44 of the embodiment shown inFIG. 4 or the lever 111 of the embodiment shown in FIG. 5 can operatethe valve of a vacuum actuator, which in turn moves the carburetorthrottle valve; such an arrangement requires less power from thesynchronous motors and amplifiers.

FIG. 6 shows a diagram of the electric circuitry that may be used withthe frequency differential-accumulator illustrated in FIG. 4. As shownin the diagram, the two flux-sensors 26 and 27 mounted on the auto areeach connected to amplifiers 51 and 52, respectively. The amplifiedsignals travel to a mixing amplifier 53 where they are combined andfurther amplified and then conducted to the actuating synchronous motor35 of the frequency differential 33. The signals also travel tothreshold relays 54 and 55, respectively, and if the signals are highenough in magnitude, they operate the threshold relays to the conditionshown in FIG. 6.

Thus, when an automobile25 travels on highway 10 in adequately closeproximity to the stripe to obtain control signals of useable amplitude,the flux sensors 26 and 27 develop a signal that actuates the thresholdrelays. In all likelihood, when an automobile begins travel on acontrolled highway, thelever 44 will be resting against one of the stops47 and switch 48. The driver has been advised of the speed required totravel on the highway by reading signs or maps, and he accelerates orslows his car to that speed. As the car reaches and slightly passes thecontrol speed, (exceeds or becomes slower than, depending on whether thecar was originally traveling slower or faster, respectively, than thecontrol speed) the discrepancy in frequency between theflux-sensor-derived signal and the standard signal causes the lever 44to lift off the stop 47 and actuate the switch 48, whereupon a rangelight 57, mounted on the dashboard of the automobile and electricallyconnected from the threshold relay 55 through the switches 48 to ground,is illuminated. (In an alternative arrangement, the driver may, throughoperation of a switch or button mounted on the dashboard, actuate amechanism to center the lever 44 between the stops 47.)

Illumination of the light 57 indicates to the driver of the automobilethat he may switch on his automatic guidance system. He does so bypushing the button 58, which is also mounted on the dashboard. Closingthe pushbutton 58 completes a circuit from the automobile battery toground through line 59 and switches 60 and 62, and then through various'parts of the automobile guidance system: the coil 64 of a solenoid-basedmagnetic coupling 65 that connects the lever 44 of the frequencydifferential-accumulator to the throttle valve of the carburetor; twoexternal lamps 67 and 68 which reveal to other drivers that theautomobile 25 is being controlled by an automatic guidance system; andthe coil 71 of a solenoid that holds the button 58 in closed position.With the system thus energized, signals developed in the flux-sensors 26and 27 are compared to a standard frequency by means of the frequencydifferential-accumulator 33 to operate the lever 44 and control thespeed of the automobile.

The vehicle 25 may be taken out of the control of the automatic guidancesystem by several alternative ways. If the operator of the vehicleeither presses the brake pedal or the accelerator pedal, he opens one ofthe switches 60 and 62, respectively. Thereupon, the magnetic coupling65 between the frequency differential 33 and the throttle valve 46 isdisconnected (whereupon, if the driver is not pressing the acceleratorpedal, a return spring 72 tends to return the throttle valve to the idleposition).

The operator may remove the automobile at his own volition or he may bewarned to do so. For example, if the system is malfunctioning in someway so that the second synchronous motor 35 gets too far behind thefirst, the lever 44 will strike one of the switches 48 and switch itfrom its position in FIG. 6. Thereupon, the dashboard light 57 willdarken and a circuit to ground will be completed through a thermalflasher 73, the tail light 74 of the automobile 25, a take-control"light 75 mounted on the dashboard, and a warning buzzer 76. The driverwill then assume control of the car and steer it out of the controlledlane. The warning devices are also actuated when the automobile deviatessufficiently from the regular course that the amplitude of signaldeveloped in either fluxsensor 26 or 27 is too low to hold its thresholdrelay 54 or 55, respectively, in the condition shown in FIG. 6.

Frequency differential-accumulators of the invention have other usesthan in automobile speed-controlling devices. For example, they may beused to control the frequency of the current generated in agasoline-engine power plant. In such a control system, the windings ofthe reference motor are supplied a standard signal such as from areference oscillator and the windings of the actuating motor aresupplied a portion of the current generated in the power plant. If thefrequency of the generated current varies, the speed of the gasolineengine is changed to correct the frequency of the generated signal; ifleft uncorrected, the variation in frequency would prevent thesatisfactory operation of devices on the system driven by synchronousmotors, such as clocks, etc.

l. A frequency differential-accumulator for comparing as to frequency astandard electric signal and an electric signal derived inmagnetic-flux-sensors on an automobile passing through a patternedsequence of magnetic fields along a highway, comprising (1) a referencesynchronous electric motor and an actuating synchronous electric motorthat each comprise a stator, an armature rotatively mounted within thestator, and electrically conductive windings carried on at least one ofthe stator and armature that may be supplied an electric current tocause rotation of the armature relative to the stator, the windings ofthe reference motor being connected to a source of current having astandard frequency and the windings of the actuating motor beingsupplied by the fluxsensor-derived signal whereby the rate of saidrotation for the reference motor corresponds with the rate of saidrotation for actuating motor when the frequencies of the derived andstandard signals correspond; (2) connection means physically connectingthe reference and actuating motors so that one of the stator andarmature of the actuating motor is fixed with respect to one of thestator and armature of the reference motor, and so that the rate ofrotation of the other of the stator and armature of the actuating motordiffers from the rate of rotation of the other of the stator andarmature of the reference motor in proportion to any lack ofcorrespondence between the frequencies of the standard and derivedsignals; and (,3) an output member drivingly connected to the other ofthe stator and armature of the actuating motor so as to be moved inproportion to any lack of correspondence between the frequencies of thederived and standard signals.

2. A frequency differential-accumulator of claim 1 in which (a) theconnection means includes a rigid couple attaching said one of thestatorand armature of the reference motor to said one of the stator andarmature of the actuating motor, (b) the other of the stator andarmature of the reference motor is adapted to be fixed with respect tothe automobile body, and (c) the output member is attached to the otherof the stator and armature of the actuating motor.

3. A frequency differential-accumulator of claim 1 in which (a) theconnection means includes means adapted to attach said one of the statorand armature of the actuating motor and said one of the stator andarmature of the reference motor to the automobile body, (b) differentialgear means are connected between the other of the stator and armature ofthe actuating motor and the other of the stator and armature of thereference motor, and (c) the output member is connected to a portion ofthe differential gear means that moves in response to any difference inthe rates of rotation of said others of the frequency a standardelectric signalarid the electric signal 7 derived in the flux-sensors,comprising (1) a reference synchronous motor and an actuatingsynchronous motor that each comprise a stator an armature rotativelymounted within the stator, and electrically conductive windings carriedon at least one of the stator and armature that maybe supplied anelectric current to cause rotation of the armature relative to thestator, the windings of the reference motor being connected to a sourceof current having a standard frequency and the windings of the actuatingmotor being supplied by the fluxsensor-derived signal whereby the rateof said rotation for the reference motor corresponds with the rate ofsaid rotation for the actuating motor when the frequencies of thederived and standard signals correspond; (2) connection means hysicallyconnecting the reference and actuating motors so t at one of the statorand armature of the actuating motor is fixed with respect to one of thestator and armature of the reference motor, and so that the rate ofrotation of the other of the stator and armature of the actuating motordiffers from the rate of rotation of the other of the stator andarmature of the reference motor in proportion to any lack ofcorrespondence between the frequencies of the standard and derivedsignals; and (3) an output member drivingly connected to the other ofthe stator and armature of the actuating motor so as to be moved inproportion to any lack of correspondence between the frequencies of thestandard'and derived signals, and (D) linkage means linking the outputmember to a throttle of the automobile so that movement of, the outputmember adjusts the speed of the automobile.

5. A combination of claim 4 in which,,in the frequencydifferential-accumulator, (a) the connection means includes a rigidcouple attaching said one of thestator and armature of the referencemotor to said one of the stator and armature of the actuating motor, (b)the other of the stator and armature of the reference motor is fixedwith respect to the automobile body, and (c) the output member isattached to. the other of the stator and armature of the actuatingmotor.

6. A combination of claim 4 in which, in the frequencydifferential-accumulator, (a) the connection means includes meansattaching said one of the stator and armature of the actuating motor andsaid one of the stator and armature of the reference motor to theautomobile body, (b) differential gear means are connected between theother of the stator and armature of the actuating motor and the other ofthe stator and armature of the reference motor, and (c) the outputmember is connected to a portion of the differential gear means thatmoves in response to any difference in the rates of rotation ofsaidothers of the stator and armature of the actuating and referencemotors.

